A pipe wrench is the conventional tool for plumbing installations and heating and ventilation engineering and is used when working on pipes and the fastening elements used when fitting pipes (sockets, union nuts, etc.). The pipe wrench is self-clamping as a result of its lever mechanism, a knurled nut on the lower lever arm adjusting the opening width of the pipe wrench such that the handle and the clamp no longer need to be pressed together in order to grip the workpiece firmly. The clamp is moved to rotate the workpiece. The wrench has to be turned round to rotate in the other direction and the position of the gripping teeth is only designed to operate in one direction.
Pipe wrenches differ in the way they operate. Pipe wrenches are distinguished according to the orientation of their opening area (90° or 45°) and the shape of their jaws (straight for gripping objects with parallel surfaces, such as nuts, straight and curved for gripping objects with parallel surfaces or round objects and s-shaped for gripping round objects).
The pipe wrench with continuous rapid adjustment is a further modification. In this case the opening width is not varied by means of the knurled nut, but by simply moving the wrench arm in the opened position and by engaging said arm on a toothed rack in the closed position.
German Patent DE 699 29 952 T2 discloses a pipe wrench consisting of two wrench bodies. The wrench bodies have clamping jaws which rotate one below the other around a rotary shaft and can be displaced with respect to one another on a recess provided on one of the wrench bodies. The rotary shaft contains a latch which represents a unilateral multiple toothed arrangement and an actuating arm to unlock the teeth if the user so desires. The latch comprises a spring which locks the teeth until the actuating arm is moved by the spring impacting with the arm on which a groove is provided.
DE 10 2006 010 234 A1 describes a pipe wrench with a protected forced guidance system. The pipe wrench consists of a first and a second wrench arm. The first wrench arm has a longitudinal slot. The second wrench arm and a guide pin formed on a second jaw are guided through this longitudinal slot. The first wrench arm also has a latching body which is formed by the slot which is parallel to the forced guidance system and by at least one latching tooth provided on the trunnion. The forced guidance system is located on the movable jaw and is formed by two opposite, plane support surfaces parallel to the wrench pivot pin and located at the side of the first wrench arm.
U.S. Pat. No. 1,401,931 discloses a pipe wrench in which the handle and the clamp can be displaced with respect to one another in a guide means. The jaws are at one end of the handle or clamp and the grip shaft is at the other end. By actuating the wrench, the jaws are moved together to grip or apart to release. The guide means consists of an element with a slot. The joint pins around which the handle and the clamp can be moved are provided such that they can each be displaced in the slot. Thus the width of the jaws can also be adjusted for rough adjustment purposes in addition to pivoting around the joint pins in each case. The guide means which is formed by the slot is curved in the direction of the jaws in this case. As a result the jaws achieve an optimum position with respect to one another. The element itself with its outer surface forms part of the gripping surface and is correspondingly toothed like the gripping surfaces of the jaws.
A pipe wrench having a handle with a first shaft-like grip part, at one end of which a first jaw is provided, is known under the registered trade name of COBRA XL/XXL pipe and water pump wrenches, item No. 8701400, from Knipex-Werke C. Gustav Putsch KG in Wuppertal. The pipe wrench also has a clamp with a second shaft-like grip part, at one end of which there is arranged a second jaw which is formed with an appropriately complementary gripping surface with respect to the first jaw. In this pipe wrench the handle and the clamp are formed such that they can pivot with respect to one another around a pivot pin. The pivot pin is in this case formed in a displaceable manner by an adjusting mechanism in a slot on the handle. The slot is curved in an opposite direction to the gripping direction.
German utility model DE 200 20 980 U1 discloses a water pump wrench in which the gripping surfaces of the jaws form a diamond-shaped opening. The joint pin, around which the handle of the water pump wrench is designed to pivot, is provided such that it can be displaced in a slot on the clamp of the wrench to allow rough adjustment of the jaws.
German utility model 1600060 discloses a water pump wrench in which the gripping surfaces of the jaws form two diamond-shaped gripping openings. The joint pin of the clamp is arranged in a toothed slot on the handle such that it can be displaced and adjusted.